Package security is a major concern of purveyors, shippers, and consumers of all types of products. Packages are frequently opened and their contents removed while in transit, in storage, or even on the store shelf. Packages whose security has been violated are often resealed to avoid suspicion and remove any outward evidence of tampering or pilferage. In consequence, it is difficult to determine where in the chain of distribution the theft or tampering occurred. Tamper-evident tapes enable manufacturers, shippers, and retailers to determine where the breach occurred and take appropriate measures to root out the person or persons responsible. Tamper-evident tape is also valued by consumers of food stuffs or other products wrapped in bags or pouches for it provides assurance that the product was not opened or adulterated prior to purchase.
Due to congressional action requiring 100% screening of all cargo moving on passenger aircraft, the U.S. Transportation Safety Administration (TSA) has explored various options for securing cargo and other items. The TSA and other organizations are constantly developing new systems, devices, and techniques for securing cargo. Tamper-evident tape may offer such a solution. One of the problems with existing tapes is that they are found to fail in many transportation security applications. Most existing tamper-evident tapes also leave very little image or residue and some simply fall off the target cargo (i.e., adhesion does not work). An effort was therefore made to standardize and treat potential strength such as ensuring that adhesion is sufficient for such tapes to remain on target cargo and other items.
Experiments and additional research have been conducted regarding to provide tests and standardization for tamper-evidence tapes to satisfy ISA performance standards. Industry standards for most physical properties of such tapes (e.g., adhesion, tensile strength, etc.) have been developed. However, additional work remains regarding analyzing patterns and residue left behind from such tapes, as will be explained
It is well known that a high percentage of tamper-evident tape is damaged during transport and that tamper-evident tape and/or associated labels do not sufficiently seal consolidated cargo. Additionally, from an operational perspective, such tamper-evident tape and labels are extremely time-consuming to apply. From a detection perspective, it is generally difficult to identify a manipulated or damaged tamper-evident tape. Additionally, residue left by tamper-evident tapes and labels preclude use to seal reusable containers.
Tamper-evident tapes that leave behind a pigmented or physical residue when removed provide a relatively inexpensive and low weight way to secure cargo and other kinds of packages and contains. Purchases of such tapes may involve a large cost investment based on the amount of goods required to be secured. Although several kinds of tamper-evident tapes are available commercially, there is no government or industry standard that suggests an optimal amount of pigment transferred by the tamper-evident tape, and the effectiveness of the transfer, as well as manufacturer's claim, vary widely.
Several devices have been discussed for measuring the adhesion of tapes, but these do not measure the transfer of pigment. See, for example, U.S. Pat. No. 7,913,552 and U.S. Pat. No. 5,673,586, which are incorporated herein by reference. In addition, some existing devices for measuring adhesion require components that are based on the measurement of a physical force. None of these approaches and/or devices employs a visual or pattern analysis approach. It is therefore believed that a need exists for an objective measure of the effectiveness of the pigment transfer in tamper-evident tapes for use in security situations such as TSA applications.